Electrical resistance element



Patente l Nov. 25, 1941 Chicago Development Company, Chicago, 111., a corporation of Illinois No Drawing.

7 claims.

Application October '23, 1939, sci-m No. 300,800

.This invention relates to electric resistance;

elements prepared from alloys comprising principally manganese and which may be worked into suitable shapes such as sheets, wire, and the like, for use in electrical circuits where various combinations are desired of electrical resistance, temperature coefficients thereof, and mechanical properties such as high strength and modulus of elasticity.

I have found that when manganese, particularly highly pure manganese such as electrolytic manganese, as hereinafter disclosed, is alloyed with more than about 2% but less than about 25% of another element or elements selected from the group copper and nickel, ductile alloys are obtained which may berolled, drawn or otherwise fabricated into wires, sheets or other suitable shapes. Such alloys in the case, quenched or cold worked state, in general, have resistances from about 65 10 ohms/cm. to about 200x ohms/cm I have also found that the electrical resistance of these'alloys may, in general, be greatly increased by heat treatment. An eflective heat treatment comprises quenching the alloys from between about 800 degrees C. and the melting point and reheating'to temperatures above approximately 300 degrees C. By such treatment, exceptionally high resistances may be obtained.

The following table is illustrative of alloys produced in accordance with my invention. It will be understood, however, that these examples are in no way to be construed as limitative of my invention, the scope of which is pointed out in the appended claims.

of these alloys is not substantially altered by the heat treatment to improve the electrical resistance. The thermo-electric force when measured against copper varies from approximately 6 micro ohms per degree to OJat 20% nickel.

These alloys, when heat treated to give resistances above 200x10 ohm/cmF, are likely to exhibit some brittleness. They should, therefore, in general, be worked into the final form in which they are to be used before they are given the final heat treatment.

The alloys showing very high resistance (above 300x10 ohms/cm!) do not, in general, have especially attractive mechanical properties. All

of the alloys in quenched, cold worked and heat treated condition, which have resistances of not more than about 200x10- ohms/cm exhibit high strength (of the order of 100,000 lbs. per square inch). In general, they also have high vibration damping capacities in all states.

The temperature coeflicient of electrical resistance of these alloys is especially interesting. Some of the quenched and cold worked alloys show temperature coeflicients of electrical resistance higher than 30x10 ohms/ohm/deg. C. In general. the temperature coefficient of electrical resistance of the alloys in this state increases regularly with the manganese content. When the alloys are heat treated to give maximum resistance, the temperature coeflicient falls oil. to an extent roughly proportional to the resistance. With resistances of approximately 500x10 ohms/cm, the temperature coeflicient of electrical resistance is'approximately 3.0x10- ohms/ohm/deg. C. At 1500 10- ohms/cm}, the

This table illustrates the effect of the presence of copper and nickel. It will be evident that considerable improvement may be obtained in the electrical resistance of alloys containing as much as 20% of either copper or nickel alone.

I have found that the thermo-electric force Reaistaneexmohms/cm. Composition Qucnch- Temperature KC.) to which alloys ing quenched were heated temperaoy turc 0. Mn Ni Cu. 400 600 600 700 800 electrical circuits. The extremely high resistance of certain of these alloys coupled with a low In the practice of my invention, I prefer particularly to use pure manganese such as electrolytic manganese and, in the examples of alloys given hereinabove, the manganese employed was electrolytic manganese having a purity of 99.9+ I have found, in general, that dimculty is frequently experienced in obtaining the results which I have described it ordinary commercity sources of silico thermic or alumino thermic manganese are used. Hence, while in the broadest aspects of my invention, I may use any suitable manganese, I have, nevertheless, found it especially desirable to use high purity manganese, namely, at least about 99.5% pure, in producing ductile alloys of very high manganese content.

While the impurities introduced by the use of ordinary commercial silico thermic or alumino thermic manganese appear to be particularly deleterious, I have found that small amounts of other metals such as zinc, tin, aluminum, iron and chromium do not exert an adverse eifect on.

at least most of the properties of the alloys of my invention.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. An electrical resistance alloy, capable of being drawn into wire or' sheet form, comprising an alloy containing at least 75% but not more than about 98% manganese, and substantially all of the balance being at least one of the elements selected iron the group consisting of nickel and copper.

- 2. An electrical resistance element in the form or a sheet or wire and consisting or a ductile alloy containing at least 90% but not more than about 98% manganese, substantially all of the balance being at least one of the elements selected from the group consisting oi nickel and copper, said resistance element having a temperature coefllcient of electrical resistance 01' at least 10x 10- ohms/ohm/deg. C.

3-. An alloy containing approximately 95% manganese, balance substantially copper and nickel, quenched from a temperature above 800 degrees C., aged at a temperature about 400 degrees C., to produce an alloy having an electrical resistance above 250x10 ohms/cmA 4. An electrical resistance element comprising an alloy, quenched from a relatively high temperature and aged above 300 degrees C., said alloy containing at least 75% but not more than about 98% manganese, and substantially all of the balance being at least one of the elements selected from the group consisting of nickel and copper.

5. An electrical resistance alloy, capable of being drawn into wire or sheet form, comprising an alloy containing at least 80% but not more than about 98% of a highly purified manganese, having a manganese content of at least 99.5 the balance of the alloy consisting essentially of at least about 2% of at least one element selected from the group consisting of nickel and copper.

6. An electrical resistance element in accordance with claim 2, wherein the manganese is electrolytic manganese having a purity of at least 99.5%.

'7. An electrical resistance element in accordance with claim 3, wherein the manganese is electrolytic manganese having a purity of at least 99.5%

REGINALD'S. DEAN. 

